Buggy code:
private static final char [ ] SEMICOLON = new char [ ] { ';' } ; TypeBinding [ ] expectedTypes ; boolean assistNodeIsClass ; boolean assistNodeIsException ; boolean assistNodeIsInterface ; CompletionParser parser ; ICompletionRequestor requestor ; ProblemReporter problemReporter ; char [ ] source ; char [ ] token ; boolean resolvingImports = false ; boolean insideQualifiedReference = false ; int startPosition ; int actualCompletionPosition ; int endPosition ; int offset ; HashtableOfObject knownPkgs = new HashtableOfObject ( 10 ) ; HashtableOfObject knownTypes = new HashtableOfObject ( 10 ) ; Scanner nameScanner ; static final char [ ] [ ] baseTypes = new char [ ] [ ] { "boolean" . toCharArray ( ) , "byte" . toCharArray ( ) , "char" . toCharArray ( ) , "double" . toCharArray ( ) , "float" . toCharArray ( ) , "int" . toCharArray ( ) , "long" . toCharArray ( ) , "short" . toCharArray ( ) , "void" . toCharArray ( ) } ; static final char [ ] classField = "class" . toCharArray ( ) ; static final char [ ] lengthField = "length" . toCharArray ( ) ; static final char [ ] THIS = "this" . toCharArray ( ) ; static final char [ ] THROWS = "throws" . toCharArray ( ) ; static InvocationSite FakeInvocationSite = new InvocationSite ( ) { public boolean isSuperAccess ( ) { } public boolean isTypeAccess ( ) { } public void setActualReceiverType ( ReferenceBinding receiverType ) { } public void setDepth ( int depth ) { } public void setFieldIndex ( int depth ) { } } ; public CompletionEngine ( ISearchableNameEnvironment nameEnvironment , ICompletionRequestor requestor , Map settings ) { } public void acceptClass ( char [ ] packageName , char [ ] className , int modifiers ) { } public void acceptInterface ( char [ ] packageName , char [ ] interfaceName , int modifiers ) { } public void acceptPackage ( char [ ] packageName ) { } public void acceptType ( char [ ] packageName , char [ ] typeName ) { } private void complete ( AstNode astNode , Binding qualifiedBinding , Scope scope ) { } public void complete ( IType type , char [ ] snippet , int position , char [ ] [ ] localVariableTypeNames , char [ ] [ ] localVariableNames , int [ ] localVariableModifiers , boolean isStatic ) { } private Initializer parseSnippeInitializer ( char [ ] snippet , int position , char [ ] [ ] localVariableTypeNames , char [ ] [ ] localVariableNames , int [ ] localVariableModifiers , boolean isStatic ) { StringBuffer prefix = new StringBuffer ( ) ; prefix . append ( "public<seq2seq4repair_space>class<seq2seq4repair_space>FakeType<seq2seq4repair_space>{\n<seq2seq4repair_space>" ) ; if ( isStatic ) { prefix . append ( "static<seq2seq4repair_space>" ) ; } prefix . append ( "{\n" ) ; for ( int i = 0 ; i < ( localVariableTypeNames . length ) ; i ++ ) { prefix . append ( AstNode . modifiersString ( localVariableModifiers [ i ] ) ) ; prefix . append ( '<seq2seq4repair_space>' ) ; prefix . append ( localVariableTypeNames [ i ] ) ; prefix . append ( '<seq2seq4repair_space>' ) ; prefix . append ( localVariableNames [ i ] ) ; prefix . append ( ';' ) ; } char [ ] fakeSource = CharOperation . concat ( prefix . toString ( ) . toCharArray ( ) , snippet , "}}" . toCharArray ( ) ) ; offset = prefix . length ( ) ; <START_BUG> String encoding = JavaCore . getOption ( JavaCore . CORE_ENCODING ) ; <END_BUG> BasicCompilationUnit fakeUnit = new BasicCompilationUnit ( fakeSource , null , "FakeType.java" , encoding ) ; actualCompletionPosition = ( ( prefix . length ( ) ) + position ) - 1 ; CompilationResult fakeResult = new CompilationResult ( fakeUnit , 1 , 1 , this . compilerOptions . maxProblemsPerUnit ) ; CompilationUnitDeclaration fakeAST = parser . dietParse ( fakeUnit , fakeResult , actualCompletionPosition ) ; parseMethod ( fakeAST , actualCompletionPosition ) ; return ( ( Initializer ) ( fakeAST . types [ 0 ] . fields [ 0 ] ) ) ; } public void complete ( ICompilationUnit sourceUnit , int completionPosition , int offset ) { } private TypeBinding [ ] computeTypes ( Expression [ ] arguments , BlockScope scope ) { } private void findAnonymousType ( ReferenceBinding currentType , TypeBinding [ ] argTypes , Scope scope , InvocationSite invocationSite ) { } private void findClassField ( char [ ] token , TypeBinding receiverType , Scope scope ) { } private void findConstructors ( ReferenceBinding currentType , TypeBinding [ ] argTypes , Scope scope , InvocationSite invocationSite , boolean forAnonymousType ) { } private void findFields ( char [ ] fieldName , FieldBinding [ ] fields , Scope scope , ObjectVector fieldsFound , ObjectVector localsFound , boolean onlyStaticFields , ReferenceBinding receiverType , InvocationSite invocationSite , Scope invocationScope , boolean implicitCall ) { } private void findFields ( char [ ] fieldName , ReferenceBinding receiverType , Scope scope , ObjectVector fieldsFound , ObjectVector localsFound , boolean onlyStaticFields , InvocationSite invocationSite , Scope invocationScope , boolean implicitCall ) { } private void findFieldsAndMethods ( char [ ] token , TypeBinding receiverType , Scope scope , InvocationSite invocationSite , Scope invocationScope , boolean implicitCall ) { } private void findImports ( CompletionOnImportReference importReference ) { } private void findKeywords ( char [ ] keyword , char [ ] [ ] choices , Scope scope ) { } private void findMemberTypes ( char [ ] typeName , ReferenceBinding [ ] memberTypes , ObjectVector typesFound , ReferenceBinding receiverType , SourceTypeBinding invocationType ) { } private void findMemberTypes ( char [ ] typeName , ReferenceBinding receiverType , Scope scope , SourceTypeBinding typeInvocation ) { } private void findIntefacesMethods ( char [ ] selector , TypeBinding [ ] argTypes , ReferenceBinding receiverType , ReferenceBinding [ ] itsInterfaces , Scope scope , ObjectVector methodsFound , boolean onlyStaticMethods , boolean exactMatch , boolean isCompletingDeclaration , InvocationSite invocationSite , Scope invocationScope , boolean implicitCall ) { }

Fix:
String encoding = this . compilerOptions . defaultEncoding ;